In FinFET technology, a vertical “fin” of crystalline silicon is used to form the body of a transistor and a gate is formed on a sidewall of the body. When gates are formed on both sidewalls of the body, the transistor is generally referred to as a double gated FinFET.
As FinFET density increases, both the fin thickness and the gate dielectric thickness formed on the fin decreases. This presents two problems. First, thinner gate dielectrics require cleaner and crystallographically more ideal fin sidewalls than present FinFET fabrication techniques can produce. Second, when present fin fabrication techniques are applied to produce thin fins, the resultant fins are weakly attached to the supporting substrate.
Therefore, there is a need for a method of fabricating FinFETs having very thin fins that have sidewall surfaces that are crystallographically close to perfect and that overcomes the inherent structural weakness of thin fins.